拉曼效应对负折射介质中超短脉冲传输的影响

通过数值法对包含拉曼延迟响应的(3+1)维非线性薛定谔方程进行求解,研究了超短脉冲激光在负折射介质中传输时拉曼效应对自聚焦传输特性的影响,着重分析其不同与常规介质的反常传输现象.结果表明:由于负的折射率影响,拉曼效应将导致超短脉冲在自聚焦过程中频谱发生蓝移现象,这与常规介质对应情形相反;而它对负折射介质中超短脉冲的自聚焦特性的影响与常规介质相同,即拉曼效应将诱导自聚焦效应首先发生在脉冲的前沿.本文研究工作对将来利用负折射介质来操控超短光脉冲串产生、自聚焦等许多实际应用领域研究具有重要的指导意义.     

PreferentiaI Polysubstitution in Organic Soid State Reactions

We have studied a number of reactions of chlorination and alkylation of phenols in a fluid phase and in the solid state. We show the predominance of the polysubstitution when phenols react in the solid state.     

像散椭圆高斯光束的M2因子矩阵的理论与实验研究

对像散椭圆高斯光束, 传统的M²因子测量采用M_x²和M_y²来描述光束质量. 当光束绕z轴旋转, M_x²和M_y²会随之变化, 单纯采用M_x²和M_y²来评价激光光束质量并不唯一. 为此采用了像散椭圆高斯光束的M²因子矩阵, 理论推导出了在同一坐标系下光场绕z轴旋转不同角度后的M²因子矩阵, 找出了光场旋转前后的M²因子矩阵元的不变量关系. 数值模拟、 实验测量得到M²因子矩阵主对角元随光斑旋转角度的变化轨迹曲线, 及反对角元随旋转角度的变化规律. 理论推导与实验结果相符. 结果表明, 像散椭圆高斯光束在主方向上时M_x²与M_y²之和最小; 在其他方向上的M_x², M_y²之和大于在主方向上的M_x², M_y²之和; 反对角元随旋转角度呈周期变化, 在主方向上为零. 关键词： M²因子矩阵')" href="#">M²因子矩阵 像散椭圆高斯光束 实验测量 矩阵光学     

Enhancing electrooptic modulators using modulation instability

As electronic operating frequencies increase toward the terahertz regime, new electrooptic modulators capable of low‐voltage high‐frequency operation must be developed to provide the necessary optical interconnects. This Letter presents a new concept that exploits modulation instability to compensate for the intrinsically weak electrooptic effect, χ⁽²⁾. Simulations demonstrate more than 50 times enhancement of electrooptic effect at millimeter wave frequencies leading to a substantial reduction in the required modulation voltage.

     

Review of optical fiber couplers

The present trends are toward implementation of fiber optics in data-distribution networks such as data buses, community antenna television, and local area networks. The thrust is, therefore, on high-volume and economical production of good quality optical fiber couplers. This paper reviews the various techniques for making fiber couplers. Important characteristics of various constructions and configurations together with their merits and demerits are discussed.     

Integrated optoelectronic circuit forecast

A market research study was conducted, leading to a 10-year forecast of worldwide integrated optoelectronic circuit (IOEC) market and application trends. Four IOEC categories were considered: lightwave, imaging array, digital IC interface optical bus, and other devices. It was concluded that worldwide IOEC production will reach $1.71 billion by 1997. It was also concluded that lightwave IOECs will be the leading device category, with commercial communication the leading application.     

High Sensitivity Ring Resonator Gyroscopes

Abstract

A recent study discussing different ring-resonator- and fiber-based gyroscopes concluded that the performance of a single-loop resonant fiber-optical gyro exceeds that of more complex ring-resonator-based gyros. It is demonstrated here that this conclusion applies as well to a gyro that consists of a closed loop of coupled-ring resonators with internal feedback. While this device is more sensitive to rotation than other gyro structures with the same footprint and losses, a simpler alternative consisting of a resonant single ring with an area equal to complex gyro structures still displays a higher degree of sensitivity.     

大气湍流对天文望远镜光电导行精度的影响

讨论了由大气湍流造成的望远镜导行误差,这一误差将给望远镜光电导行的精度带来较大影响。其中使用单点源目标的导行精度受限于大气相干长度和大气相干时间,而多点源目标及面源的导行精度还与湍流随高度的变化有关。通过分析和仿真(数值模拟)结果表明,现代天文观测必须考虑大气湍流对光电导行精度的影响。通过延长曝光时间可以有效降低湍流大气的影响,同时也降低了光电导行的反馈控制频率。当导行信标为多星或面源则可在一定程度上降低高层大气湍流带来的光电导行误差,从而可以适度减少光电导行曝光时间,提高其反馈控制频率。     

Aspects on Applications of IR Reflectivity- and Raman Scattering-Experiments on Polaritons in Solid State Chemistry and Biophysics

The coupled phonon-photon state called “polariton” is an elementary excitation which exists at all temperatures in single crystalline materials with well defined translational symmetries. In the view of this aspect polaritons turn out to be more important for the dynamics of crystal lattices in general than e.g. magnons or plasmons which normally can be excited only in certain low temperature ranges. The present article summarizes experimental results which all might be applied as analytical methods. An improved method for the determination of fundamental mode frequencies is described. Polariton interactions with localized modes, and second order phonons and the relation to the ferroelectric phase transition mechanism is reviewed. Furthermore experiments concerning parametric light scattering, the TM-reflection technique, the ATR-method, and nonlinear optical experiments are summarized. We finally discuss the question of mechanical-electromagnetic energy conversion and some tentative future aspects.     

Quantum states transfer between coupled fields

We study the exchange of states in coupled fields along their time evolution. The coupling is described by a quadratic form in terms of annihilation and creation operator in the field Hamiltonian. An analytical approach is employed to describe the time evolution of the field state in Fock's space and the conditions for an arbitrary initial states to be transferred with 100% fidelity is determined. We show that only for initial states C₀|0>+C_N|N>, this situation can occurs. The important |1〉↔|0〉 qubits transfer is a particular case of this transference of number state. The relation between the coupling constant and characteristic field frequencies for complete state transference is also determined.